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Kawano, Toshihiko

Publications and source records attributed to Kawano, Toshihiko.

Consistent $\overline{ν}$ evaluation for minor Pu isotopes with CGMF

This report follows up on the evaluation work done in 2023 where we developed a procedure and performed the first consistent evaluation of the average prompt neutron multiplicity for minor Pu isotopes, including 238,240-242 Pu, using CGMF. Details on the necessary updates to the release version of CGMF, the experimental data and experimental uncertainty quantification that went into the evaluation, and this first evaluation effort are documented in and will not be repeated in this report. Instead, we discuss here the further investigations into the CGMF model space to improve the evaluation results from FY23. Additionally, we note that these evaluation results have been transformed into the ENDF format for mean values and covariances, and validation with critical assemblies has been performed; that work is documented elsewhere. In this short report, we discuss the updated evaluation efforts performed during FY24 in Sec. 2, show results from CGMF for other prompt fission observables in Sec. 3, and then briefly conclude in Sec. 4.

07 ISOTOPE AND RADIATION SOURCES

coh3

CoH3 (CoH ver.3) is an optical model, exciton pre-equilibrium, and Hauser-Feshbach statistical model code, which calculates nuclear reaction cross sections for medium to heavy targets in the keV to MeV energy region. This program is written in standard C++, divided into approximately 200 source and header files. CoH solves the Schroedinger equation for optical potentials defined in the code, and calculates differential elastic scattering, reaction, and total cross sections, for neutron, proton, deuteron, triton, 3He, and alpha-particle. Deformed optical potentials are solved with the coupled-channels method, in which the ground state rotational band members, or vibrational phonon states are coupled. The optical model gives particle transmission coefficients that are fed into the statistical model calculations. CoH includes the pre-equilibrium model (exciton model), the direct/semidirect capture model, and the multi-stage Hauser-Feshbach statistical decay with width fluctuation correction based on the Gaussian orthogonal ensemble. For weakly coupled levels, the DWBA (distorted wave Born approximation) method is used to calculate the direct inelastic scattering process to the excited states.

Kawano, Toshihiko

Chlorine Nuclear Data Evaluation Aided Through New LANSCE Measurements

The collaboration between the Los Alamos National Laboratory Neutron Science Center (LANSCE) and TerraPower LLC enables the enhanced understanding of fast spectrum critical systems consisting of chlorine. Specifically, TerraPower is interested in updating the nuclear data for the stable isotopes of chlorine, 35 Cl and 37 Cl, because these nuclides are the primary constituents of the chloride fuel salt in the Molten Chloride Reactor Experiment (MCRE), for which TerraPower is leading the design. The Cooperative Research and Development Agreement (CRADA) between the parties is funded by DOE’s Office of Nuclear Energy’s Gateway for Accelerated Innovation in Nuclear (GAIN) initiative to provide the nuclear community with access to the technical, regulatory, and financial support necessary to motivate innovative nuclear reactor technologies toward commercialization. New measurements of 35 Cl(n,p total ) and 35 Cl(n,α total ) were completed at LANSCE to constrain the reaction theory models that are used to generate the updated evaluations. The updated evaluations were then tested across the sensitivities of the MCRE by TerraPower to provide direct feedback to the evaluation for application specific sensitivities.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA